P. HIV Ag-Ab, Enzygnost HIV Integral, Enzymun-Test HIV Combi, Genscreen HIV 1/2, version 2 (third-generation EIA), and Genetic Systems HIV-1 Ag EIA (p24 antigen assay). VIDAS HIV DUO Ultra showed a comparable sensitivity to the single p24 antigen assay in seroconversion panels and a dilution series of computer virus lysates. The diagnostic windows was reduced with VIDAS HIV DUO Ultra by 3.82 days, CP 31398 2HCl on average, in comparison with the fourth-generation assay with the lowest sensitivity of the antigen detection module. HIV-1 contamination was detected 5.88 days earlier than with third-generation EIA. The mean time delay between reverse transcription-PCR and VIDAS HIV DUO Ultra was only 2.31 days. The specificity of fourth-generation assays after retesting ranged between 98.1 and 100%. In conclusion, VIDAS HIV DUO Ultra can replace single-antigen screening for laboratory diagnosis and screening of HIV contamination in blood donors. There was no evidence for a second diagnostic windows due to impaired sensitivity of the antibody detection module of all the fourth-generation CP 31398 2HCl EIAs evaluated in the present study. The specificity after initial and/or repeated screening of VIDAS HIV DUO Ultra was equivalent to that of a third-generation assay. In order to reduce the diagnostic windows period between the time of human immunodeficiency computer virus (HIV) contamination and laboratory diagnosis, new testing enzyme-linked immunosorbent assays which permit the simultaneous detection of HIV antigen and antibody have been introduced around the international market (4, 8, 9, 11, 13, 16, 17, 21, 23-25, 27). Combined antigen and antibody assessments show a higher sensitivity for the detection of main HIV contamination than conventional assessments in urban centers with high HIV incidences and prevalences (15). Although this new assay generation represents a major improvement in terms of sensitivity in comparison to the former generation through a imply reduction of the diagnostic windows by 4 days (4, 8, 9, 11, 13, 16, 23-25, 27), optimization of the overall performance characteristics is usually requested for different reasons. Combined assays for antigen and antibody detection cannot substitute single-antigen Rabbit Polyclonal to RIN1 assessments for blood donor screening. The detection limit of fourth-generation assays (20 to 100 pg of p24 antigen [Ag]/ml) is usually higher than that of antigen assays (3.5 to 10 pg of p24 Ag/ml). Highly sensitive antigen assays detect primary infection on average 1 to 2 2 days earlier than fourth-generation enzyme immunoassays (EIAs) (26). The antigen detection module of fourth-generation assays shows a variable sensitivity for detection of different HIV type 1 (HIV-1) non-B subtypes, including group O, and CP 31398 2HCl HIV-2 (1). Some assays may fail to detect low-level antigens of HIV-1 non-B subtype strains, although monoclonal antibody is usually directed against conserved epitopes of p24 Ag (13, 25). Since the genetic diversity of HIV is usually rapidly increasing worldwide, including in industrialized countries, fourth-generation assays need to be optimized in order to accurately detect all HIV-1 subtypes and HIV-2. A further potential risk for impaired sensitivity is usually that a more-limited space of the solid phase can be utilized for antibody detection since about one-third of the binding sites are occupied by anti-p24 antibody for HIV antigen detection; therefore, the antibody detection module may be less sensitive than single third-generation antibody assays. Antibody detection may be delayed in seroconversion panels without antigenemia, and a second diagnostic windows may be observed in the early seroconversion phase when low antibody titers are present and antigenemia declines (11). Since fourth-generation EIAs combine two different test principles in one assay, the potential risk for nonspecific reactivity may be higher than for second- and third-generation antibody assays. The rate of false-positive results obtained with blood donors and interfering samples varies from 0.3 to 0.8% (versus a maximum of 0.2% for third-generation EIAs), depending on the donor background (1). Fourth-generation assays demand a special algorithm for the analysis of reactive samples. For the anti-HIV part of the assay, confirmation of reactivity should be carried out first with an assay that lacks the p24 Ag detection module, and when reactivity persists, immunoblotting should be used. For the p24 Ag part, confirmation of reactivity should be analyzed in an assay CP 31398 2HCl that lacks the anti-HIV detection part and when reactivity persists, a nucleic acid-based assay should be used. Confirmation of this a part of reactivity is usually hampered by the fact that actually none of the commercially available nucleic acid-based assays is able to detect CP 31398 2HCl HIV-1 group O and the HIV-2 genome. The new VIDAS HIV DUO Ultra, which has an improved sensitivity of the antigen detection module and has also improved antibody detection through a double sandwich.